ICSP (2) questions

[mvs_sarma]

I am trying (without success, of course) to use ICSP, using Low Voltage.

To help to make it work, would some sweet soul answer some of my questions ?

a) can I use RS-232 to program a 18F452 ? What voltage is required ?

I guess I can, as here there is a LVP

>>> http://home.vrweb.de/~lotharstolz/st...vpc/index.html

But I'd like to know the voltage required to make it work, as I have no success,
and my WorkStation only provides 10 volts on the RS-232 interface ...

b) can I program the 18f452 with the crystal installed ?

I guess I can, as the final circuit has to have a crystal and I must be able to re-program it on the board, but I have read it is better not to have the crystal when programming.

I am using MPASM and IC-PROG under XP. Thanks. Ramon.

1. LVP is not that important unless the device under concern can't take 13V programming. BTW, LVP eats off one pin of Port B and you can't use it in your program anywhere.
2. ICSP you need to momentarily disable few pins used otherwise for the circuit you design.
regards to oscillator, many times PIC18xxxx uses internal oscillators. perhaps, then you need something called Vpp before Vdd facility. so that the circuit wont start and the device is taken to program mode.

The best appears, PICKIT2. if you have time and patience to make few adopters, you don't need the other two parts you referred in your earlier post. Perhaps from spare components lying at home one can make these adopters. Incidentally, if money is nothing before the time lost, you may of course have them

Please put your schematic here and let us see why you are not able to use ICSP facility, Ramon.

[Ramonetnet]

mr Sarma : (I think) I did not say I can not use it (because of my design).
I was trying to say I can not use it because I don't know the electric diagram for it !
(All that stuff about oscillator and Vpp versus Vss...)
Sorry for the misunderstanding !

[mister_e]

See page 31 of the PICkit2 user guide
http://ww1.microchip.com/downloads/e...Doc/51553E.pdf

This should be enough.

[mvs_sarma]

See page 31 of the PICkit2 user guide
http://ww1.microchip.com/downloads/e...Doc/51553E.pdf

This should be enough.

Many a time I have tried but always the download stops before reaching 1,7MB out of 2.08MB or so. Perhaps Microchip may have to replace it.

[mister_e]

Weird... never had any download problem myself

Anyways, when you buy a PICKIT 2, it's on the CD.

I'd post the following suggestion really often here.

http://www.melabs.com/support/icsp.htm

Ok it's for MElabs programmer, but the idea is the same.

Microchip solution... the one in the PDF
<img SRC="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=2542&stc=1&d=120915241 1">

Almost the same... but the last one don't talk about the load on PGM pin, and don't show the cap on Vdd.. which is not important... but mandatory!

[Ramonetnet]

Mr_E : you are very kind.
But while I was waiting for your help,
I did some patch tests and ... it works

( I open'd a thread called "LVP for 18f452" ...)

What it says is I melted 2 designs
(1) http://home.vrweb.de/~lotharstolz/st...vpc/index.html
(2) http://www.josepino.com/pic_projects...programmer.jpc
and here you are : a working LVP for 18F452 ! (see attached JPG)

Maybe it is not impressive to you, experimented people,
but it has been and still is a great satisfaction to me,
everytime a ".hex" file is moved to the PIC and the LEDs
(now there are plenty of them : a 7-segment + "dot")
and then does what it is suposed to do.

Microchip people almost got my money, but I prefer this way : forums, patch board, Google.

Thank you all !

[Ramonetnet]

mr Sarma : the file is there (2.177.632 bytes without a problem)

c: >wget http://ww1.microchip.com/downloads/e...Doc/51553E.pdf
--03:17:11-- http://ww1.microchip.com/downloads/e...Doc/51553E.pdf
=> `51553E.pdf'
Resolving ww1.microchip.com... done.
Connecting to ww1.microchip.com[194.224.66.25]:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2,177,632 [application/pdf]

100%[====================================>] 2,177,632 309.55K/s ETA 00:00

03:17:18 (309.55 KB/s) - `51553E.pdf' saved [2177632/2177632]